Universal temperature dependence of the thermal conductivity of clathrate compounds, molecular crystals, and glasses at low temperatures

Korolyuk, O. A.; Кривчиков, А. И.; Romantsova, O. O.

doi:10.1063/10.0000528

“…The ultra‐low κ throughout the measured temperature range (2–711 K) identified to be glass‐like (Figure S1b, Supporting Information) [24] . The broad plateau in measured thermal conductivity data further indicates that the thermal conductivity of crystalline AgSbSe 2 exhibits the characteristic of an amorphous material [7c, 25] . This necessitates investigating the periodicity of AgSbSe 2 in atomic scales (local scale) to explain such an ultra‐low κ lat .…”

Section: Resultsmentioning

confidence: 99%

Local Symmetry Breaking Suppresses Thermal Conductivity in Crystalline Solids

Dutta

¹

,

Prasad

²

,

Pandey

³

et al. 2022

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Understanding the correlations of both the local and global structures with lattice dynamics is critical for achieving low lattice thermal conductivity (κlat) in crystalline materials. Herein, we demonstrate local cationic off‐centring within the global rock‐salt structure of AgSbSe2 by using synchrotron X‐ray pair distribution function analysis and unravel the origin of its ultralow κlat≈0.4 W mK−1 at 300 K. The cations are locally off‐centered along the crystallographic ⟨100⟩ direction by about ≈0.2 Å, which averages out as the rock‐salt structure on the global scale. Phonon dispersion obtained by density functional theory (DFT) shows weak instabilities that cause local off‐centering distortions within an anharmonic double‐well potential. The local structural distortion arises from the stereochemically active 5s2 lone pairs of Sb. Our findings open an avenue for understanding how the local structure influences the phonon transport and facilitates the design of next‐generation crystalline materials with tailored thermal properties.

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Local Symmetry Breaking Suppresses Thermal Conductivity in Crystalline Solids

Dutta

¹

,

Prasad

²

,

Pandey

³

et al. 2022

View full text Add to dashboard Cite

Understanding the correlations of both the local and global structures with lattice dynamics is critical for achieving low lattice thermal conductivity (κlat) in crystalline materials. Herein, we demonstrate local cationic off‐centring within the global rock‐salt structure of AgSbSe2 by using synchrotron X‐ray pair distribution function analysis and unravel the origin of its ultralow κlat≈0.4 W mK−1 at 300 K. The cations are locally off‐centered along the crystallographic ⟨100⟩ direction by about ≈0.2 Å, which averages out as the rock‐salt structure on the global scale. Phonon dispersion obtained by density functional theory (DFT) shows weak instabilities that cause local off‐centering distortions within an anharmonic double‐well potential. The local structural distortion arises from the stereochemically active 5s2 lone pairs of Sb. Our findings open an avenue for understanding how the local structure influences the phonon transport and facilitates the design of next‐generation crystalline materials with tailored thermal properties.

show abstract